Fabricated PVC-U fittings for Potable Water Supplies, Part 8: Specific Requirements for 90-degree Bends
2009 Edition

IS 10124 Part 8 defines the dimensions for fabricated PVC-U 90° bends intended for potable water systems. Key parameters include the bend radius (R), typically three times the nominal outside diameter (D), nominal pipe sizes, wall thickness matching pipe specifications, and overall lengths ensuring smooth flow and minimal pressure loss. For instance, nominal sizes such as 20 mm, 50 mm, and 110 mm have bend radii around 1.5 to 2 times D with corresponding lengths approximately 60 mm, 150 mm, and 300 mm. These dimensions assure hydraulic efficiency and compatibility. Detailed dimension tables and tolerances are available within the standard.

The standard encompasses pressure classes ranging from 0.4 MPa (Class 2) up to 1.25 MPa (Class 6). Wall thickness requirements increase proportionally with the pressure class to maintain structural integrity under higher pressures. For each nominal pipe size, minimum wall thicknesses are specified per class. For example, a 100 mm nominal size bend may require approximately 2.3 mm thickness at 0.4 MPa and up to 6.7 mm at 1.25 MPa. Thickness values are calculated as 90% of the corresponding pipe’s minimum wall thickness, rounded up to the nearest 0.1 mm, ensuring safety margins.

Socketed ends for 90° bends are optional according to IS 10124 Part 8. Bends may have plain ends at both sides or be socketed at one or both ends based on agreement between manufacturer and purchaser. When socketed, the dimensions must comply with specifications in IS 10124 Part 1. Importantly, for pressure class 0.25 MPa, bends should be manufactured from pipes rated at 0.4 MPa rather than 0.25 MPa to ensure adequate performance.

Each 90° bend shall be permanently marked with the manufacturer's name or identification, the nominal size, pressure class as per IS 4985, and the bend degree (90°). Additionally, color coding indicates the pressure rating: blue for Class 2 (0.4 MPa), green for Class 3 (0.6 MPa), brown for Class 4 (0.8 MPa), yellow for Class 5 (1.0 MPa), black for Class 6 (1.25 MPa), and pink for plumbing fittings. This marking system facilitates easy identification and traceability within piping assemblies.

The fittings must be fabricated from unplasticized PVC (PVC-U) compliant with IS 4985:2000, ensuring suitability for potable water with non-toxic, corrosion-resistant properties. Manufacturing processes should maintain dimensional accuracy, avoid contamination, and produce smooth internal surfaces to prevent microbial growth and promote efficient flow. Markings including manufacturer identification, size, pressure rating, and relevant IS standard numbers are mandatory. Quality assurance involves testing physical, mechanical, and chemical properties per IS 10124 Part 1, guaranteeing compliance with potable water safety standards.

No, pipes with a 0.25 MPa pressure rating should not be used to fabricate 90° bends. Instead, bends for such pressure classes must be made from pipes rated for at least 0.4 MPa. This requirement ensures sufficient strength and durability at critical bend points within the water distribution system, enhancing safety and compliance with IS 10124.

IS 10124 Part 8 focuses on specific requirements for fabricated PVC-U fittings, particularly 90° bends, and references IS 10124 Part 1 for general requirements such as materials, sizes, testing, and conformity criteria. IS 4985 specifies standards for unplasticized PVC pipes used in potable water systems. Together, these standards provide a comprehensive framework ensuring compatibility and uniform quality between pipes (IS 4985) and their corresponding fabricated fittings (IS 10124 parts), facilitating reliable potable water infrastructure.